Tab key when indenting with spaces does not insert correct number of spaces

[rgov]

• VSCode Version: 1.45.0
• OS Version: macOS Catalina 10.15.4

This is a re-filing of #80129 which was closed erroneously. This is NOT caused by an extension and reproduces when editing even a plain text document when extensions are all disabled.

Related to #2798.

If the insertion point is anywhere inside the indentation at the start of the line, and I press Tab, the indentation should be increased to the next full tab stop (multiple of the tab width).

I'll use the period . character instead of spaces in indentation so that it is easier to see what I'm talking about.

If I have a line of code indented by 4 spaces like this:

....do_something()

If I place the insertion point on column 2 and press tab, I get 7 spaces. That's really irritating, it means I have to be hyper precise placing my cursor when I want to indent a line, even when there's a very wide click target I should be able to hit anywhere.

.......do_something()

Xcode does this properly, it increases the indentation to 8 spaces and moves the cursor to the end of the indentation. TextMate behaves the same as Xcode.

Does this issue occur when all extensions are disabled?: Yes

[rgov]

I do have editor.useTabStops enabled but I don't understand what it does if not this.